(PhysOrg.com) -- Blind musicians have had restricted access to scores due to the scarcity and limitations of Braille transcriptions. A new European system makes music for the blind more available and far easier to use.

An international team of scientists, led by researchers at the University of California, San Diego School of Medicine have discovered new links between a common form of inherited blindness affecting children and a gene known ...

(PhysOrg.com) -- The findings bolster the claims by some scientists, like Stanford's Brian Wandell, who say certain visual abilities must develop properly in childhood and cannot be learned as an adult.

(AP) -- Three universities testing Amazon's Kindle in the classroom have agreed to shelve the electronic book readers until they are fully functional for blind students, under a deal struck Wednesday with the Justice Department.

Ask anyone who suffers from migraine headaches what they do when they're having an attack, and you're likely to hear "go into a dark room." And although it's long been known that light makes migraines worse, the reason why ...

A research team led by a Michigan State University professor has discovered a link between diabetes and bone marrow nerve damage that may help treat one of the disease's most common and potentially blindness-causing complications.

This week's edition of The Lancet sees the first in a four-part Series on Neglected Tropical Diseases (NTDs) -- conditions which almost exclusively affect the world's poorest people, namely those 2.7 billion people living ...

Need a little extra incentive to kick the habit? Just in time for New Year's resolutions, a UCLA study finds that even after age 80, smoking continues to increase one's risk for age-related macular degeneration (AMD), the ...

Blindness

Blindness is the condition of lacking visual perception due to physiological or neurological factors.

Various scales have been developed to describe the extent of vision loss and define blindness. Total blindness is the complete lack of form and visual light perception and is clinically recorded as NLP, an abbreviation for "no light perception." Blindness is frequently used to describe severe visual impairment with residual vision. Those described as having only light perception have no more sight than the ability to tell light from dark and the general direction of a light source.

In order to determine which people may need special assistance because of their visual disabilities, various governmental jurisdictions have formulated more complex definitions referred to as legal blindness. In North America and most of Europe, legal blindness is defined as visual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet (6.1 m) from an object to see it—with vision correction—with the same degree of clarity as a normally sighted person could from 200 feet (61 m). In many areas, people with average acuity who nonetheless have a visual field of less than 20 degrees (the norm being 180 degrees) are also classified as being legally blind. Approximately ten percent of those deemed legally blind, by any measure, have no vision. The rest have some vision, from light perception alone to relatively good acuity. Low vision is sometimes used to describe visual acuities from 20/70 to 20/200.

By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, low vision is defined as visual acuity of less than 6/18 (20/60), but equal to or better than 3/60 (20/400), or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction. Blindness is defined as visual acuity of less than 3/60 (20/400), or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.

It should be noted that blind people with undamaged eyes may still register light non-visually for the purpose of circadian entrainment to the 24-hour light/dark cycle. Light signals for this purpose travel through the retinohypothalamic tract, so a damaged optic nerve beyond where the retinohypothalamic tract exits it is no hindrance.